The following description is provided to assist the understanding of the reader. None of the information provided or references cited is admitted to be prior art to the present invention.
Blood vessels are assembled by two processes known as vasculogenesis and angiogenesis. In vasculogenesis, a primitive vascular network is established during embryonic development from endothelial cell precursors called angioblasts. Angiogenesis involves preexisting vessels sending out capillary buds or sprouts to produce new vessels. Angiogenesis is an important process critical to chronic inflammation and fibrosis, to tumor cell growth, and to the formation of collateral circulation. Angiogenesis is involved in the normal process of tissue repair.
Tissue engineering involves the use of living cells to develop biological substitutes for tissue replacement. However, in order for tissue engineering to be practical, scaffolds must be developed that allow for tissue growth that approximates natural tissue growth. Vascularization is necessary to enable tissue engineering to be used in applications that require structures greater than 0.5 mm thick. The controlled growth of vascular networks requires the timed release of multiple growth factors throughout the maturation process. In vivo, the relative timing, quantity, and location of growth factor release is regulated as part of a complex biological system.